1) Field of the Invention
The field of the present invention generally relates to lighting systems and, more particularly, to a vehicle headlight and control system as may be used in connection with, among other things, large vehicles and conveyances such as buses, trucks, streetcars, and the like.
2) Background
Proper road illumination is an important factor in allowing drivers to identify potential road hazards. Transit vehicles, trucks and other large vehicles or conveyances generally employ headlights for providing illumination at nighttime, dusk or in other situations of reduced visibility. Such headlights are typically forward-facing and thus illuminate primarily in a forward direction, but with some spread of light fanning out slightly towards either side. Vehicle headlights commonly include low beams used for general purposes, and high beams that may be manually activated in situations requiring additional illumination.
Because glare from headlights may adversely affect oncoming traffic, transportation regulatory authorities dictate the extent to which headlight illumination can spread outward, both in terms of angular spread and intensity. Headlight manufacturers generally must comply with such regulations and design headlight illumination patterns accordingly.
For large vehicles, such as buses and trucks, drivers are more prone to experiencing blind spots while driving or maneuvering. This may occur, for example, where a bus driver attempts to make a right turn. The driver may have a difficult time spotting pedestrians crossing a street, or about to cross a street, particularly at nighttime, dusk or other low light situations. Likewise, a pedestrian may be unaware that a bus or other large vehicle is about to make a turn across the path where the pedestrian is walking. This lack of visibility presents a potentially dangerous situation in which serious injuries can occur. Since buses spend considerable time navigating in crowded urban settings, they are at higher risk for encountering these potential situations. While these problems are more significant for buses and other large vehicles, they are also experienced albeit to a lesser degree with smaller vehicles as well.
Some attempts have been proposed for improving side visibility when a vehicle is in the process of turning. For example, under one approach, a headlight reflector is mechanically tilted sideways as a vehicle turns, based on a detected steering wheel angle. While this approach may improve visibility during turning, it requires a mechanical means to tilt the headlight reflector, and mechanical parts can be prone to wear and tear or mechanical failure, typically require an electronic control means, and can increase the cost of a headlight unit. Also, merely adding side illumination may be insufficient to warn pedestrians that a vehicle is about to, or in the process of, making a turn.
Other related approaches include the provision of additional lighting sources to supplement the amount of light provided at a side angle as the vehicle turns. However, those additional lighting sources may involve additional lighting fixtures or units, thus increasing cost and complexity.
In addition, many headlights are based on halogen or high-intensity discharge (HID) light sources. These light sources may have certain drawbacks, such as excessive energy consumption or frequent replacement requirements.
Although prior attempts have attempted to solve the aforementioned problems, they are either costly, complex, incomplete, or inadequate particularly for larger vehicles. It would therefore be advantageous to provide a vehicle headlight and control system that solves one or more of the aforementioned problems, and/or is less complex or costly, more reliable, more energy efficient, longer lasting, and well suited for use in larger vehicles.